Q: Loud knocking noise and engine is shaking.

asked by on January 18, 2017

After accelerating down the road yesterday, mistakenly turned O/D "off" and tried to pass a slow-moving car. Engine revved up without gaining speed, then kicked back, followed by a loud repetitive knocking sound (as well as the check engine light flashing). Vehicle now continues to knock loudly whenever idling, and becomes noticeably louder when opening the throttle (accelerating/decelerating). Oil was low (so topped it off), and is still making noise. The noise appears to be coming from the engine and nowhere else on the car.

My car has 150000 miles.
My car has an automatic transmission.

Hi there. When passing a vehicle and turning off the overdrive at the same time with the pedal on the floor will be like trying to shift a vehicle without the clutch in a manual transmission driven vehicle. The rpm’s spike to the max and make the engine have a red line. What probably happened is the engine spun a rod bearing or damaged the engine causing the knocking noise. Check the codes on the ECM (computer) to see what is stored. When the check engine light flashes that means that the issue is happening right at that moment. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose an engine knock.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Engine stalls and now won’t start up

Unfortunately an engine can really fail at any time for any number of reasons regardless of what year or how many miles it has on it, but it for sure isn’t normal. Toyota has a number of things that can...

What's the purpose of thermostat in a car?

Hi There, The thermostat regulates the flow of the coolant in your car's engine and controls when the coolant flows in and out of the motor from the radiator by opening and closing at specific temperatures. When your thermostat is...

The car has a whining sound?

Hello - the whining in lower gears you hear is likely a worn bearing in the transmission. Acceleration in lower gears puts far higher pressure on transmission bearings, which wear over the miles. If the noise seems excessive, or is...

Related articles

P0062 OBD-II Trouble Code: HO2S Heater Control Circuit (Bank 2 Sensor 3)
P0062 P0062 trouble code definition Trouble code P0062 indicates that the heater circuit used to warm up an oxygen sensor has malfunctioned. A voltage ranging from 12.0-13.5 and a ground connection is required to operate the oxygen sensor. The cause...
P0490 OBD-II Trouble Code: Exhaust Gas Recirculation "A" Control Circuit High
P0490 means the PCM has detected an abnormally high voltage within the exhaust gas recirculation system, often due to clogging.
P0795 OBD-II Trouble Code: Pressure Control Solenoid C
P0795 means that a fault with the electronic pressure control solenoid, or the solenoid circuit, has occurred due to a faulty solenoid, or low fluid.